Impression control device



Oct. 6, 1959 Filed July 9, 1957 FIG! L. P. FRECHETTE IMPRESSION CONTROL DEVICE 2 Sheets-Sheet l VENTOR FRECHETTE ATTb NEYS Oct. 6, 1959 L. P. FRECHETTE 2,907,436

IMPRESSION CONTROL DEVICE Filed July 9, 1957 2 Sheets-Sheet 2 NVENTOR P. FRECHE Zia/jg ATTORNEYS IMPRESSION CONTROL DEVICE Leo P. Frechette, Newington, Conn., assignor to Royal McBee Corporation, PortChester, N.Y., a corporation of New York Application July 9, 1957, Serial No. 670,771

9 Claims. (Cl. 197-17) This invention relates to an impression control device for typewriters and like machines, and more particularly relates to a novel apparatus for controlling the printing impact of the various type bars of an electric typewriter.

During normal typing operations ink in the typewriter ribbon is transferred to the paper being typed on by applying an impact pressure to a portion of said ribbon. This impact pressure is. created by the successive striking action of various type bars against the inked ribbon which overlies the paper supported in the typewriter carriage. In that the ink in said ribbon is pressure sensitive, it is apparent that the intensity of print on said paper may be varied by changing. the impact pressure applied to said ribbon. Such a variation in impact pressure may be obtained by varying the kinetic energy. finally imparted to each of the successively actuated type bars 0 the machine.

Various devices have been proposed for varying the amount of kineticenergy possessed by each type bar as it strikes the ribbon. Many of these proposals contemplate the provision of adjustable means for varying the amount of kinetic energy imparted in the first instance to said bars. Such means being part of the various type bar actuating linkages are apt to be complex and expensive, particularly if variable impact pressures are to be provided for upper case as well as lower case letters. Likewise, such arrangements may easily get out of adjustment.

One object of the instant invention is to provide an improved reliable impression control device for power operated typewriters.

Another object of the invention is to provide an adjustable apparatus for controllably diminishing the amount of kinetic energy which has been initially imparted to each actuated type bar of the machine.

Another object of the invention is to provide a resilient means for controllably absorbing a portion of the kinetic energy of the actuated type bars as the latter respectively approach the typewriter platen.

A further object of the invention is to provide an impression control system whereby each actuated type bar initially receives a substantially constant impulse and thereafter receives a predetermined restraining action.

Other objects of the invention will become apparent as the disclosure progresses.

In the drawings:

Fig. 1 is a side elevation showing the parts of the in stant device and their functional interrelation with the related elements of the typewriter.

Fig. 2 is a side elevation view of the apparatus of Fig. 1 showing the relative positions of said parts during the typing of upper case letters.

It will be understood that unless otherwise stated the various hereinafter described mechanisms and parts thereof are suitably supported by the main side frames of the machine in a manner well understood in the art.

In that the impression control device for each of the chine.

23,907,436 Patented Oct. 6, 1959 type bars of the typewriter is similar, a detailed description of one thereof will suffice here.

In Fig. 1 there is shown a type bar actuating linkage 8 comprising a bell crank or member 9 which is rotatably mounted on the shaft 10. Articulately connected to the upper end of the bell crank is a first link 11 which is connected in the usual fashion to a pivotally mounted type bar. A second link 12 articulately connected to said bell crank actuates the typewriter ribbon feed mechanism in a manner well understood in the art. The bell crank or sub-lever 9 is provided with a rearwardly extending arm 15 having a bent over pad or abutment shoulder 16 formed on the end thereof. Pivotally mounted on the cross shaft 20 are two identical levers 21. Said levers are axially spaced along said shaft 20, and are interconnected for concomitant movement by shafts and 26 which are secured to and between the upper and rearward arms 27 and 28 of said levers respectively.

Disposed between and supported by said levers is a shaft 30 which pivotally supports a bail .31 having a forwardly extending body portion 32. Secured to the bail body portion 32 is a plurality of laterally aligned fingers or support elements 35, each one of said fingers being associated with one of the normal complement of bell cranks 9. Each finger 35 is made of a plastic material, preferably nylon, and threadedly supports two adjustable contact screws 36 and 37 which are respectively selectively positionable, in a manner described below, so as to lie in the path of movement of the said bent over pad 16 of the associated bell crank 9. The frictional contact between said plastic material and the respective contact screws 36, 37 is sufficient to overcome any tendency for screws 36, 37 to vibrate out of a given adjusted position. One end of bail 31 is provided with a rearwardly extending arm 40 which underlies a fixed abutment stud 41 that is suitably fixedly secured to the frame of the ma- The bail 31 is biased in a counter clockwise direction by means of a spring 43 which is anchored at its lower end to the fixedly mounted stud 44; the limit of the counter clockwise movement of bail 31 being determined by engagement of said arm 40 with the stud 41.

Rearwardly disposed of said shaft 20 is a cross shaft which is rotatably supported in the machine frame. Rotatably secured to shaft 50. is a crank 51 having two radially extending arms 52 and 53 which are respectively provided with headed pivot studs 55 and 56 A pair of arms 58 and 59 are swingably mounted on said studs 56 and 57 respectively. It will be noted that the upper arm 58 is pivotally supported on the lower stud 56 while the lower arm 59 is pivotally supported on the upper stud 55. The respective rearward extensions 60 and 61 on said arms 58 and 59 are yieldably interconnected by means of a spring 62 so as to bias the respective forward ends 64, 65 of said arms 58 and 59 into opposed clamping engagement with the shaft 26 that interconnects said levers 21.

A lever is rotatably secured to said shaft 50 and is pivotally connected to a link 71. Link 71 is in turn operatively connected to the linkage of the case shift mechanism of the typewriter whereby operation of said shift mechanism serves to rotatably actuate shaft 50.

In operation, each of the various bell cranks 9 are successively actuated in a counterclockwise direction. As each bell crank 9 approaches the end of an operational stroke the bent over pad 16 is intercepted by the associated contact screw 36 which, during the typing of lower case letters, is normally disposed in the path of travel of said pad 16. As the bell crank continues to rotate the bail 31 will be rocked in a clockwise direction, as shown by the dotted lines of Fig. 1, against the biasing action of said spring 43. Hence, during the terminal portion of the travel of each actuated bell crank 9'and its associated type bar a part of the kinetic energy initially imparted thereto will be absorbed by the restraining action of spring 43. The remaining portion of said kinetic energy is utilized for the printing action of said type bar. In that a substantially uniform impulse is initially imparted to each of the actuated type bars and related linkages of an electric typewriter, the amount of kinetic energy possessed by the type bar as it strikes the typewriter ribbon may be varied by changing the amount of mechanical energy which is absorbed by the spring 43. It will be apparent that for any given type bar this variation may be obtained by properly rotatably adjusting the related contact screw 36 so that the engagement of pad 16 with screw 36 occurs earlier or later in said operative stroke of the bell crank 9. By appropriately adjusting all of the various contact screws 36, the desired printing impact for each of the type bars of the machine may be obtained. 7 I

When upper case letters are to be printed the typewriter case shift mechanism is operated; such actuating the link 71 which in turn will rotate shaft 50. Rotation of shaft 59 will, through arms 58, 59 and shaft 26, rock the levers 21 thereby forwardly translating the bail 31 so as to position the contact screw 37 in the path of travel of said pad 16 of bell crank 9 as shown in Fig. 2. Contact screw 37 may be adjusted in a manner similar to that for screw 36 so that spring 43 will exert a predetermined restraining action on the type bar before the bell crank pad 16 elevates finger 35 to a clockwise limit of travel as indicated by the dotted lines of Fig. 2. When the case shift mechanism is restored to its normal condition, finger 35 will be translated rearwardly so that the contact screw 36 is again positioned in the path of travel of pad 16.

It will be noted that the arms 58 and 59 and the spring 62 constitute a yieldable rotary connection between the shafts 20 and 50. This type connection is provided so that should pad 16 ever be in its upper position wherein it interferes with either the forward or rearward shifting movement of said screws 36, 37 the shaft t) may complete its rotary case shift travel and the terminal portion of the translational shifting movement of the bail 311. and screws 36, 37 may be completed under the action of spring s2 after said pad is removed from said upper position.

It has been found that the instant apparatus, in addition to being inexpensive, is reliably accurate.

While there is in this application specifically described one form which the invention may assume in practice, it will be understood that this form of the .same is shown for purposes of illustration only and that the invention may be modified and embodied in various other forms without departing from its spirit or the scope of the appended claims.

The invention claimed is:

1. In a power operated typewriter having an upper and lower case letter shift mechanism, a plurality of individually movable type bars, and a plurality of power operated linkages for respectively actuating said type bars; the improvement comprising, a pair of adjustable resiliently supported contact screws associated with each of a plurality of said linkages, each of said screws being mounted for selective movement into and out of the path of travel of t a portion of the associated linkage, and means responsive to the actuation of said case shift mechanism for moving one of each of said pairs of screws into said path.

2. In a power operated typewriter having an upper and lower case shift mechanism, a plurality of movable type bars, a plurality of linkages for respectively actuating said type bars, and a power means for selectively driving said linkages; the improvement comprising', a plurality of pairs of stops respectively associated with said linkages, each pair of stops being selectively positionable to respectively engage a part of each of said linkages during the terminal portion of the operative travel thereof to thereby reduce the kinetic energy previously imparted to said type bars by said power means, and means responsive to the actuation of said case shift mechanism for selectively positioning said stops.

3. In a power operated typewriter having a frame, a plurality of movable type bars, and a plurality of linkages for respectively actuating said type bars, each of said type bars and its associated actuating linkage being provided with an impression control device comprising, a support element movably supported by said frame, means for biasing said element in one direction to a normal position, adjustable means mounted on said support element and normally lying in the path of movement of a part of said linkage so as to resiliently intercept the terminal portion of the travel of said part, and yieldably. operable means for shifting the position of said support element.

4. In a typewriter having a frame, a plurality of movable type bars, a plurality of linkages for respectively actuating said type bars, each of said type bars and the associated linkage being provided with an im* pression control device comprising, a finger movably mounted on said frame, a pair of adjustable contact screws supported by' said finger, the movement of said finger being adapted to position said screws one at a time in the path of travel of a part of said linkage, and spring means connected to said finger for restraining the motion of said linkage.

5. In a typewriter having a frame, a plurality of movable type bars, a plurality of linkages for respectively actuating said type bars, and an upper and lower case shift mechanism, each of said type bars and the associated linkage being provided with an impression control device comprising a finger movably supported by said frame, a pair of contact screws adjustably mounted on said finger, spring means biasing said finger to one directional limit of movement, and means actuated in response to the operation of said case shift mechanism for moving said finger to a position wherein one of said screws lies in the path of travel of a portion of the associated one of said linkages.

6. In an electric typewriter having a frame, a plurality of movable type bars supported in said frame, a plurality of linkages for respectively actuating said type bars, an upper and lower case shift mechanism, an impression control device comprising, a shaft movably supported by said frame, at least one finger pivotally mounted on said shaft, a pair of adjustable contact screws supported by said finger and each adapted to be moved by displacing said shaft into one of two positions wherein said screws respectively lie in the path of a portion of an associated one of said linkage, spring means rotatably biasing said finger to onerotational limit of movement, and means actuated in response to the operation of said case shift mechanism for yieldably moving said shaft.

7. In a typewriter having a frame, a plurality of type bars movably mounted on said frame, a plurality of linkages for respectively actuating said type bars, and a case shift mechanism; the improvement comprising, a shaft swingably mounted on said frame, a plurality of fingers pivotally mounted on said shaft, means for yieldably biasing said fingers to one rotational limit of movement, a pair of contact screws adjustably mounted in each of said fingers, the swinging movement of said shaft being adapted to selectively position one of each of said pairs of screws in the path of travel of a portion of an associated one of said linkages, yieldable means for swinging said shaft, and means responsive to the operation of said case shift mechanism for actuating I saidlast mentioned means.

8. In a typewriter, having a case shift mechanism, a plurality of individually movable type bars, and a plurality of linkages for respectively actuating said type bars; the improvement comprising, at least one finger, means supporting said finger for translational movement, means supporting said finger for rotational movement, adjustable means mounted on said finger and adapted to lie in the path of movement of a part of one of said type bar actuating linkages, means for rotatably biasing said finger, and means responsive to the operation of said case shift mechanism for actuating said finger translating support means.

9. In a typewriter having a case shift mechanism, a plurality of individually movable type bars, and a plurality of linkages for respectively actuating-said type bars; the improvement comprising, at least one finger, means supporting said finger for translational movement,

References Cited in the file of this patent UNITED STATES PATENTS 1,179,464 Sholes 1- Apr. 18, 1916 r 2,697,502 Becker Dec. 21, 1954 2,750,022 Long ..a..------- June 12, 1956 

